U.S. patent number 5,742,692 [Application Number 08/407,433] was granted by the patent office on 1998-04-21 for in-the-ear hearing aid with flexible seal.
This patent grant is currently assigned to U.S. Philips Corporation. Invention is credited to Joseph F. J. M. Beumers, Rudi A. M. Claes, Henri Garcia.
United States Patent |
5,742,692 |
Garcia , et al. |
April 21, 1998 |
In-the-ear hearing aid with flexible seal
Abstract
An in-the-ear hearing aid has a collar which can form a flexible
seal in the bony part of the ear canal so as to reduce the
occlusion effect. The collar comprises a tubular portion which is
engageable against the wall of the ear canal, a fixing portion and
a curved sealing portion. Owing to the use of this collar it is not
necessary to make a mold of the bony part of the ear canal. This
collar enables the hearing aid to be constructed in a manner such
that it can be inserted so deep into the ear.
Inventors: |
Garcia; Henri (Eindhoven,
NL), Beumers; Joseph F. J. M. (Eindhoven,
NL), Claes; Rudi A. M. (Eindhoven, NL) |
Assignee: |
U.S. Philips Corporation (New
York, NY)
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Family
ID: |
8216782 |
Appl.
No.: |
08/407,433 |
Filed: |
March 17, 1995 |
Foreign Application Priority Data
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Apr 8, 1994 [EP] |
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94200961 |
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Current U.S.
Class: |
381/328;
381/322 |
Current CPC
Class: |
H04R
25/652 (20130101); H04R 25/658 (20130101); H04R
25/456 (20130101) |
Current International
Class: |
H04R
25/00 (20060101); H04R 25/02 (20060101); H04R
025/00 () |
Field of
Search: |
;381/68,68.5,68.6,68.1,69,69.1,69.2,60,23.1 ;181/129,130,135 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0533258 |
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Mar 1993 |
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EP |
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0043700 |
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Mar 1983 |
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JP |
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1173657 |
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Dec 1969 |
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GB |
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WO9325053 |
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Dec 1993 |
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WO |
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Primary Examiner: Le; Huyen D.
Attorney, Agent or Firm: Eason; Leroy
Claims
We claim:
1. An in-the-ear hearing aid comprising:
a housing containing an electro-acoustic transducer, wherein the
housing has a comparatively wide portion situated near a first end
of the housing and adjoining a comparatively narrow portion
situated near a second end of the housing, the hearing aid being
adapted to fit partly in a fleshy part and partly in a bony part of
a user's ear canal and to form, during use, a seal for the ear
canal in the bony part thereof, wherein to form the seal in the
bony part of the ear canal the hearing aid includes a collar which
is fixed to the housing by means of a fixing element, wherein the
collar comprises;
a tubular outer portion made of a flexible material and which, at a
side remote from the first end of the housings ends in a curved
portion made of a flexible material which in turn ends in a tubular
inner portion coaxially arranged with respect to said tubular outer
portion, wherein the fixing element extends at least partly inside
of the tubular inner portion and has a largest radial dimension
(d1) which is substantially smaller than a corresponding inner
dimension (d2) of the tubular outer portion, and wherein
the narrow portion of the housing extends at least partly inside of
the tubular outer portion.
2. An in-the-ear hearing aid as claimed in claim 1 further
comprising a vent which connects a space surrounded by the tubular
portion of the collar to an aperture in the first end of the
housing so as to eliminate any static pressure difference between
said space and the environment of the user of the hearing aid.
3. The in-the-ear hearing aid as claimed in claim 1 wherein said
tubular outer portion has a length of at least 2 mm and a diameter
constant throughout its length, and said tubular inner portion of
the curved portion is connected to the fixing element.
4. The in-the-ear hearing aid as claimed in claim 1 wherein the
tubular outer portion is arranged to engage the bony part of the
wall of the user's ear canal,
a part of the narrow portion of the housing and a part of the
electro-acoustic transducer extend inside of the tubular outer
portion, and
the curved portion functions as a diaphragm which is radially
compressible so as to seal said bony part of the ear canal.
5. The in-the-ear hearing aid as claimed in claim 1 wherein the
fixing element is secured to the tubular inner portion and a
cross-section of the collar has approximately a U-shape.
6. The in-the-ear hearing aid as claimed in claim 1 wherein a part
of the electroacoustic transducer extends inside of a part of the
tubular outer portion, the largest radial dimension of the fixing
portion is at most 70% of the corresponding inner dimension of the
tubular outer portion, and the largest radial dimension of a part
of the hearing aid housing which extends inside the tubular outer
portion of the collar is at most 70% of a corresponding inner
dimension of the tubular outer portion.
Description
BACKGROUND OF THE INVENTION
This invention relates to an in-the-ear hearing aid comprising a
housing and at least one electroacoustic transducer, which housing
has a comparatively wide portion situated near a first end of the
housing and adjoining a comparatively narrow portion situated near
a second end, which hearing aid is adapted to be fitted partly in a
fleshy part and partly in a bony part of the ear canal and to form
a seal for the ear canal in the bony part of the ear canal during
use.
Such a hearing aid is known from WO93/25053 (herewith incorporated
by reference). The known hearing aid has a rigid housing provided
with a cover of a soft synthetic material. The rigid housing
accommodates the normal hearing-aid components such as a
microphone, an amplifier, a trimmer for adjusting the volume, an
electroacoustic transducer for converting an electric signal into
sound, and a battery. The housing has a comparatively wide portion
which begins at a first end and a comparatively narrow portion
which terminates in a second end. During use the wide portion is
situated in a substantially fleshy part of the ear canal and the
narrow portion is situated in a substantially bony part of the ear
canal. In order to preclude undesirable acoustic feedback care must
be taken to avoid acoustic leakage between the microphone and the
electroacoustic transducer via a gap between the walls of the
hearing aid and the ear canal. However, if the ear canal is sealed
the user often complains of his own voice sounding hollow and
booming. This so-called occlusion effect can be mitigated by
arranging a seal as close as possible to the ear-drum. For this
purpose the cover of the known hearing aid has such a shape at the
location of the second end that near the ear-drum it can provide
acoustic sealing of the space into which the transducer radiates
its sound. In order to provide a satisfactory adaptation to the
shape of the wall of the ear canal the cover is made of a soft
polymer. However, upon deformation, since the cover has a thick
wall at the location of the seal, the environment of the cover will
be subjected to a force which increases strongly with the
deformation. In addition, the bony part of the ear canal is of
irregular shape and substantially non-deformable. In order to
preclude discomforting stress on the wall of the ear canal, the
above-mentioned cover should be shaped by means of a mould of the
fleshy and bony part of the ear canal of the individual user. A
method of making such a mould is described in EP-A-0,533,258 (PHN
13.848), which corresponds to U.S. application Ser. No. 943,366,
filed Sep. 10, 1992. A mould of the fleshy part can readily be made
and differences in the shape of the hearing aid and the ear canal
can be accommodated to some extent because the walls of the fleshy
part are somewhat deformable. Making a satisfactory mould for the
bony part is very difficult because the mould is liable to be
deformed when it is removed from the ear owing to the substantially
non-deformable walls of the bony part. Besides, small differences
in the shape of the hearing aid and the bony part of the ear canal
are likely to give rise to leakage of the seal or to uncomfortable
pressure on the wall of the ear canal. Moreover, making a mould of
the bony part often causes much discomfort to the user because it
strains the ear-drum and the bony part is very susceptible to
pressure.
Another problem of the known hearing aid is that jaw action of the
user of the hearing aid may cause leakage of the seal. During jaw
movement the fleshy part moves relative to the bony part so that
locally the hearing aid is pressed to one side of the ear canal and
a gap may be formed at the other side. Particularly in the case of
hearing aids with a high gain this is likely to give rise to
acoustic feedback, which manifests itself as a loud squealing
sound.
One of the principal reasons why hearing aids have to be returned
to the factory is soiling of the aperture in the housing through
which the electroacoustic transducer emits its sound. This aperture
becomes clogged by ear-wax in the ear canal and therefore this
ear-wax should be removed at regular intervals by the user. Since
the ear-wax hardens after some time removal may sometimes be
impossible without damage to the hearing aid. The construction of
the known hearing aid is such that the hearing aid can be repaired
only by the manufacturer or by a specialised workshop.
SUMMARY OF THE INVENTION
It is an object of the invention to improve a hearing aid of the
type defined in the opening paragraph so as to achieve an optimum
wearing comfort without a mould of the entire bony part having to
be made while a satisfactory sealing in the bony part is maintained
even during jaw movement and the seal causes few or no complaints
about the occlusion effect.
To this end the hearing aid in accordance with the invention is
characterised in that for forming the seal in the bony part of the
ear canal the hearing aid is provided with a collar comprising a
tubular portion of a flexible material having a length of more than
2 mm, a fixing portion whose largest radial dimension is
substantially smaller than the corresponding inner dimension of the
tubular portion, and a curved portion of a flexible material which
connects the end of the tubular portion which is remote from the
first end to the fixing portion.
Owing to its flexibility the tubular portion can engage against the
wall of the ear canal with a minimal pressure being exerted on the
wall of the bony part of the ear canal. Tests have revealed that a
satisfactory engagement in view of undesired acoustic feedback is
obtained if the length of the tubular portion is selected to be
greater than 2 mm. The cross-section of the ear canal is sealed by
the curved portion which acts as a diaphragm and which is radially
compressible owing to its curvature. Since the largest dimension of
the fixing portion in a radial direction is substantially smaller
than the corresponding inner diameter of the tubular portion and
the curved portion is flexible, parts of the tubular portion can
move in a radial direction without large forces, thus allowing the
tubular portion to assume, for example, an oval shape. These
features also allow the fixing portion to be off-centred in a
radial direction without large forces being exerted on the wall of
the ear canal and without the sealing action being lost. Owing to
this off-centering tolerance it is not necessary to know the exact
shape of the ear canal at the location of the seal in the bony part
and the mould need not be formed in close proximity to the
ear-drum. A mould which extends just past the second bend in the
ear duct is adequate. This off-centering tolerance is also of
importance during jaw movement of the user of the hearing aid
because the fleshy part of the ear duct is then moved relative to
the bony part, as a result of which the housing of the hearing aid
will also move relative to the bony part. With the hearing aid in
accordance with the invention undesired acoustic feedback during
jaw movement is prevented. Another advantage is that insertion and
removal of the hearing aid is more comfortable because the
compressibility of the collar allows constrictions in the ear canal
to be passed without excessive stress on the wall of the ear
canal.
U.S. Pat. No. 5,220,612 describes another in-the-ear hearing aid.
One of the embodiments disclosed therein has a flexible element at
the narrow end, which is intended to seal the ear canal. However,
in contradistinction to the seal in accordance with the invention,
this element requires the use of a mould of the ear canal.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the largest radial dimension of the fixing
portion is at the most 70% of the corresponding inner dimension of
the tubular portion. Tests have revealed that by thus limiting the
dimensions of the fixing portion satisfactory results can be
obtained as regards wearing comfort and that in addition an
effective sealing in the bony part of the ear canal is
obtained.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the electroacoustic transducer extends at
least partly inside the tubular portion. By arranging the
transducer at least partly inside the tubular portion the total
length of the hearing aid can be reduced and the first end of the
housing can be fitted deeper in the ear canal, so that the hearing
aid becomes less conspicuous.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the largest radial dimension of the part
of the hearing aid which extends inside the tubular portion of the
collar is at the most 70% of the corresponding inner dimension of
the tubular portion. By thus limiting the dimensions of the part of
the hearing aid disposed inside the tubular portion an optimum
deformability of the tubular portion is achieved, so that it can
conform to the oval cross-section of the bony part of the ear
duct.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the tubular portion and the curved portion
have a wall thickness of less than 0.5 mm. Limiting the wall
thicknesses provides a satisfactory flexibility and a high
deformability of the tubular portion and the curved portion. This
step also enables the collar to be flattened in a radial direction
to a dimension smaller than or equal to that of the fixing portion
plus 1 mm. As a result, the hearing aid in accordance with the
invention is also suitable for users having irregular and/or narrow
ear canals.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the tubular portion is rotationally
symmetrical. Such a collar can readily conform to the usually oval
cross-section of the bony part of the ear canal regardless of the
orientation of this oval cross-section. As a result, the
orientation of this cross-section of the user's ear canal need not
be taken into account when the tubular portion is fitted.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the tubular portion has an outer diameter
of between 6 and 11 mm. By providing collars of diameters in a
range between 6 and 11 mm the wearing comfort for the user can be
optimised by the choice of the appropriate collar.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the collar is detachably secured to the
housing of the hearing aid via the fixing portion. By making the
collar detachable, for example, by means of a snap, clamping,
screw-thread or bayonet connection, soiled, damaged or incorrectly
fitting collars can also be replaced by the audiologist or the
user. This enables many problems of the user to be solved locally
and at low cost.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the collar is detachably secured to the
electroacoustic transducer via the fixing portion. This embodiment
provides all advantages outlined in the above paragraph and enables
the radial dimensions of the hard parts disposed inside the tubular
portion of the collar to be reduced in order to increase the
deformability of the collar.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the tubular portion and the curved portion
comprise a viscoelastic material.
This step provides a further improvement of the wearing comfort
because in the case of deformation of an element of a viscoelastic
material the force necessary to sustain the deformation decreases
as a function of time immediately after application of the
deformation owing to a reduction of material stresses. This means
that shortly after insertion of the hearing aid the stresses on the
wall of the ear canal decrease and the hearing aid causes less
discomfort to the user.
An embodiment of the hearing aid in accordance with the invention
is characterised in that the tubular portion and the curved portion
comprise an acrylic polymer. This material can be manufactured with
a Shore A hardness of less than 20 so that it is readily
deformable. Moreover, the material can be rendered viscoelastic and
can be dyed easily. Besides, this material can be polymerised with
ultraviolet light.
An embodiment of the hearing aid in accordance with the invention
is characterised in that it has a vent which connects a space
surrounded by the tubular portion of the collar to an aperture in
the first end of the housing. This step eliminates static pressure
differences between said space and the environment of the user.
These pressure differences arise particularly when the hearing aid
is fitted into and removed from the ear canal. As a result of the
flexibility of the collar and the fact that the collar presses only
gently against the wall of the ear canal, this step will also
reduce the build-up of pressure differences between the environment
of the user and the space between the ear-drum and the collar.
An embodiment of the hearing aid in accordance with the invention,
in which the electroacoustic transducer has an aperture through
which sound can be emitted, is characterised in that the fixing
portion has at least one duct which adjoins the aperture. One of
the most frequent complaints is that the hearing aid no longer
functions correctly because the aperture through which sound is
emitted is clogged with cerumen. This embodiment prevents cerumen
from settling directly on the electroacoustic transducer. The
cerumen will now first settle in said duct in the fixing portion,
which greatly reduces the likelihood of the electroacoustic
transducer having to be replaced.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in more detail, by way of
example, with reference to the accompanying drawings, in which:
FIG. 1 shows an embodiment of the hearing aid in accordance with
the invention,
FIG. 2 is a sectional view of the ear canal with an embodiment of
the hearing aid in accordance with the invention placed
therein,
FIG. 3 is a longitudinal sectional view of the collar of an
embodiment of the hearing aid in accordance with the invention,
FIG. 4 is a sectional view of an ear canal in which a mould for
making an embodiment of the hearing aid in accordance with the
invention is disposed, and
FIG. 5 is a cross-sectional view of the collar of another
embodiment of the hearing aid in accordance with the invention.
It is to be noted that the embodiments are shown diagrammatically
and the Figures are shown to an arbitrary scale, which is not
always the same.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows a hearing aid 1 having a housing 20. The housing 20
accommodates hearing aid components, shown diagrammatically and
known per se, such as a microphone 12, an amplifier 13, a trimmer
14 for adjusting the volume, an electroacoustic transducer 15, and
a battery 16. The housing 20 has a comparatively wide portion 22
which begins at a first end 21 of the housing and which adjoins a
comparatively narrow portion 23 situated near a second end 24. A
collar 30 is secured to the hearing aid 10 and has a tubular
portion 31, a fixing portion 32 and a curved portion 33. The curved
portion 33 connects an end of the tubular portion 31 which is
remote from the first end 21 of the housing to the fixing portion
32. The tubular portion 31 and the curved portion 33 are of a
flexible material and in the present embodiment these portions are
integral with one another. The transducer 15 extends partly inside
the tubular portion 31 of the collar 30.
FIG. 2 shows diagrammatically an ear canal 1 comprising a fleshy
part 2 and a bony part 3 terminating in an ear-drum 4. The hearing
aid 10 in the ear canal 1 is adapted to be fitted partly in the
fleshy part 2 and partly in the bony part. The wide portion 22 of
the housing 20 is situated substantially in the fleshy part 2 and
forms an acoustic seal in this part. The narrow portion 23 of the
housing 20 is situated substantially in the bony part 3. In order
to preclude undesirable acoustic feedback care must be taken to
avoid acoustic leakage between the microphone 12 and the
electroacoustic transducer 15 via a gap between the walls of the
hearing aid 10 and the ear canal 1. However, if the ear canal 1 is
sealed the user often complains of his own voice sounding hollow
and booming. This so-called occlusion effect can be mitigated by
arranging a seal as close as possible to the ear-drum 4. To this
end the hearing aid 1 in accordance with the invention is adapted
to form, in addition to the seal in the fleshy part 2, another seal
in the bony part 3 of the ear canal 1. At the location of the
second end 24 the collar 30 has such a shape that it can provide
acoustic sealing in the bony part 3 near the ear-drum 4. Thus, the
space into which the transducer 15 radiates its sound is
acoustically isolated from the other parts of the ear canal 1.
Since the transducer 15 extends partly inside the tubular portion
31 of the collar 30 the hearing aid 10 can be fitted so deep that
the first end 21 of the housing 20 is disposed substantially at the
location of the first bend 6 of the ear canal 1. This provides a
result which is aesthetically very satisfactory.
FIG. 3 shows a greatly enlarged longitudinal sectional view of a
part of the housing 20 and the collar 30. The collar 30 is
detachably connected to the housing 20 by its fixing portion 32, in
the present case via a bayonet coupling. This enables the collar 30
to be replaced simply by means of a suitable tool. This is because
each radial dimension d1 of the fixing portion 32 of the collar 30
is substantially smaller than the corresponding inner dimension d2
of the tubular portion 31, so that the tubular portion can be
pressed inward locally or wholly. Preferably, the largest radial
dimension d1 of the fixing portion 32 of the collar 30 is at the
most 70% of the corresponding inner dimension d2 of the tubular
portion 31. In the present embodiment a part 29 of the hearing aid
10 also extends within the tubular portion 31 of the collar 30.
Preferably, the largest radial dimension d3 of this part 29 of the
hearing aid is also at the most 70% of the corresponding inner
dimension d2 of the tubular portion 31. These steps provide enough
room to prevent the fixing portion 32 or said part 29 of the
hearing aid from pressing against the wall 9 of the bony part 3 via
the tubular portion 31.
The tubular portion 31 has a length l of more than 2 mm. Tests have
demonstrated that this provides an adequate sealing of the ear
canal 1 to preclude undesirable acoustic feedback.
Preferably, the wall thicknesses w of the tubular portion 31 and
the curved portion 33 are selected to be smaller than 0.5 mm. This
provides a satisfactory flexibility and a high deformability of the
tubular portion 31 and the curved portion 33. This step also
enables the collar 30 to be radially flattened to a corresponding
dimension smaller than or equal to that of the fixing portion 32
plus 1 mm. As a result, the hearing aid 10 in accordance with the
invention is also suited for users with irregular and/or narrow ear
canals.
In the embodiment shown in FIG. 3 the tubular portion 31 is
rotationally symmetrical. Thus, the collar 30 can readily conform
to the usually oval cross-section of the bony part of the ear canal
1 regardless of the orientation of this oval cross-section. As a
result, the orientation of this cross-section of the user's ear
canal need not be taken into account when the tubular portion 31 is
fitted.
By providing collars 30 of outer diameters d4 in a range between 6
and 11 mm, the wearing comfort for the user can be optimised by the
choice of the appropriate collar 30.
FIG. 4 shows diagrammatically how a conventional mould 40 of the
ear canal 1 is made. A sealing plug 41 of a soft material is
introduced into the bony part of the ear canal 1 of the prospective
user of the hearing aid 10. Subsequently, a liquid material is
poured into the ear canal 1, which material cures after some time.
After curing a mould 40 is obtained, which is removed by means of
strings 42 attached to the plug 41. After the mould 40 has been
made the hearing aid 10 is manufactured as follows. The dimensions
and the shape of the wide portion 22 of the housing 20 are
determined by means of the mould 40. The narrow portion 23 of the
housing 20 is made in conformity with the orientation of the last
part 43 of the mould 40 formed just past the second bend 7 of the
ear canal 1. A suitable diameter d4 for the collar is also selected
by means of the last part 43 of the mould 40.
This method enables a part of the hearing aid 10 to be placed in
the bony part 3 of the ear canal 1 and a seal to be formed at this
location by means of the collar 30 without a mould of the bony part
having to be made. This is a great advantage because it is very
difficult to make a satisfactory mould of the bony part 3 because
the substantially non-deformable walls 9 of the bony part often
deform the mould as it removed from the ear canal 1. Moreover,
making a mould of the bony part 3 often causes much discomfort to
the user because it strains the ear-drum 4 and the bony part is
very sensitive to pressure.
FIG. 5 is a view similar to FIG. 3, showing an embodiment in which
the collar 30 is secured to the electro-acoustic transducer 15 of
the hearing aid 10 via the fixing portion 32. For this purpose the
end of the transducer 15 is provided with a coupling element 25, to
which the fixing portion 32 can be secured by means of a bayonet
coupling. Securing the collar 30 to the transducer 15 is
advantageous because the narrow portion 23 of the housing 20 can
then be thin-walled and can be made of a soft material.
The fixing portion 32 is of such a construction that it can also
function as a cerumen protector. The electroacoustic transducer 15
has an aperture 19 for radiating sound. To this end a duct 35,
which during use connects the aperture 19 to the space 8 between
the fixing portion 32 and the ear-drum 4, takes the form of a
labyrinth (see FIG. 2). This precludes serious damage, which can
arise if the transducer 15 becomes clogged with cerumen. If the
fixing portion 32 is clogged beyond repair it can readily be
replaced owing to the detachable connection.
The embodiment shown in FIG. 1 has a vent 17 which connects a space
36 surrounded by the tubular portion 31 of the collar 30 to an
aperture 18 in the first end 21 of the housing 20. This step
eliminates static pressure differences between said space 36 and
the environment of the user. These pressure differences arise
particularly when the hearing aid 10 is fitted into and removed
from the ear canal 1. As a result of the flexibility of the collar
30 and the fact that the collar 30 presses only gently against the
wall 9 of the ear canal 1 this step will also limit pressure
differences between the environment of the user and the space 8
between the ear-drum 4 and the collar 30.
It is to be noted that the invention is not limited to the
embodiments shown herein. Within the scope of the claims various
other embodiments are possible, for example by the use of a snap,
clamping or screw-thread connection for mounting the collar.
Moreover, it is obvious that embodiments can be conceived which
have, for example, a collar of oval shape.
* * * * *